@kev-m   Oh, dip switches!  I don't have the confidence to take the front off that box.

Just try room temp mode without looking at the dip switches. If it's not set to auto adapt I think it'll just act like a dumb thermostat like it's doing now.  If you want to know if it is on AA, turn up the temp a couple or three degrees and the radiators will get hotter. If it isn't, they won't.

In WC atm and if I turn the temp up on the thermostat (Mitsubishi wireless) the radiators get hotter.

Just try room temp mode without looking at the dip switches. If it's not set to auto adapt I think it'll just act like a dumb thermostat like it's doing now.  If you want to know if it is on AA, turn up the temp a couple or three degrees and the radiators will get hotter. If it isn't, they won't.

One single remote thermostat, single zone all to radiators.

Should be fine.  You need to make sure that the Room Sensor setting is set to "Main RC".  It's on the menu under Initial Settings (the little cog wheel).  You also need to enable Auto Adaptation via a dip switch. SW5-2.  The default is enabled (mine was enabled)

Have you tried just changing to Room Temp mode on the main controller in the airing cupboard?  If the two above things are in place it should just work.  You'll know because the first thing that will happen is your radiators will get much hotter for a couple of days.    

One single remote thermostat, single zone all to radiators.

From memory they are Honeywell thermostats (I'll check when I get back) and were installed by Lovell's before we moved in. I'm able to set temperature and daily programs from them which the pump seems to respond to. 

If it would help I'll ask Lovell's to provide a wireless Mitsubishi unit but only if I know it'll help. 

Regarding the WC setting...we've been using the above suggested settings for the past 4/6 weeks and haven't noticed a great deal of difference. Particularly downstairs it seems to never reach the called for temp even when left for hours. This weekend for example we left the house at 3:30pm with the thermostat showing 16.5'c...before we left I turned it up to 18'c so that when we returned in 2/3 hours the house would be warm...but when we had got back the temp had dropped to 16'c. I know the DHW hadn't been on as that's on a timer.

I don't really want the temp at night above 16.5/17'c as A. it's too warm and B. too expensive but it takes what seems like a lifetime to then get back to a decent temp. The wife is getting pretty fed up with daily bills being well in excess of £10 a day whilst still being cold, so much so she's started to consider putting in a wood burner which defeats the purpose of an eco ASHP.     

Check and set the WC curve as shown in the video below. Try initial settings of 50C LWT at -5C outside air temperature and 25C LWT at 20C outside air temperature.

https://www.google.com/search?q=how+to+set+weather+compensation+on+ecodan+heat+pump&rlz=1C1OPRB_enGB514GB552&oq=how+to+set+weather+compensation+on+ecodan&aqs=chrome.2.69i57j33i160l2.53193j1j7&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:a02b8ba7,vid:uC3jydJydRQ

Once completed open fully any TRV's in the living areas, and set any thermostats to 1C above the desired temperature.

Leave the system running for a few hours then report back what has happened to the indoor temperatures.

From memory they are Honeywell thermostats (I'll check when I get back) and were installed by Lovell's before we moved in. I'm able to set temperature and daily programs from them which the pump seems to respond to. 

If it would help I'll ask Lovell's to provide a wireless Mitsubishi unit but only if I know it'll help. 

Regarding the WC setting...we've been using the above suggested settings for the past 4/6 weeks and haven't noticed a great deal of difference. Particularly downstairs it seems to never reach the called for temp even when left for hours. This weekend for example we left the house at 3:30pm with the thermostat showing 16.5'c...before we left I turned it up to 18'c so that when we returned in 2/3 hours the house would be warm...but when we had got back the temp had dropped to 16'c. I know the DHW hadn't been on as that's on a timer.

I don't really want the temp at night above 16.5/17'c as A. it's too warm and B. too expensive but it takes what seems like a lifetime to then get back to a decent temp. The wife is getting pretty fed up with daily bills being well in excess of £10 a day whilst still being cold, so much so she's started to consider putting in a wood burner which defeats the purpose of an eco ASHP.     

my argument was the installation did not give me the full functionality of the system.