It charges at much higher pressure than normal refrigerant and is mass critical on charging, you cannot charge by monitoring the gauges.

Thanks, @ashp-bobba. That confirms me in not wanting to do it myself. Good to know.

It charges at much higher pressure than normal refrigerant and is mass critical on charging, you cannot charge by monitoring the gauges.

To be frank, I'm not keen on trying to do it myself but I'll bear it in mind when talking with the local garages that are being as helpful as they can. There are one or two that recognise they're going to have to add R744 to their repertoire, so who knows....

Understand the frustration with a less common heat pump gas.
Seems like these may help, they appear to be based in Ilford. Unusual to market it via ebay, but may help.. 

Googling it suggested BOC provide co2 canisters at reasonable price but that would probably be the start of a project. 😁

My EV is showing signs that the gas pressure in the aircon is getting low and so is struggling to cool things down properly in the hot weather. As a result, I need to get it regassed, but the problem is that it's got the optional heat pump in it and so is gassed with R744 (carbon dioxide). I'm struggling to find anywhere in the South East other than a main dealer who is equipped for this particular gas, and have wasted more than a little time with garages that say they can sort it because of the make and model before actually seeing it and realising they can't, courtesy of not listening to me initially.

Frustrating, but does anyone know of an outfit that can REALLY deal with R744, is based in the South East and doesn't charge an absolute fortune?