No wonder you regret getting it! What make is it and who installed it ? I love mine !

It's Mitsubishi and was installed by a company called heart,they went bankrupt a few years after the installation. The system is good but because there are so few engineers who expertise in that area it is difficult to get someone out. I'm just glad I kept my boiler for hot water.

I’ve never used Hive but heat pumps don’t work efficiently with third party controls. Are you running it low and slow? Ie not on a timed schedule, other than a degree or two set back at night? Do you know what COP you’re getting? Are you using weather compensation or fixed flow?

I’m sorry to hear this @Pawlu1960, once you answer the following from juliamc I’ll tag a few other Community Members who have Mitsubishi heat pumps to see if they have any advice. 

Hi. I'm running it low and slow. I'm not sure how to run it any other way, it's too complicated. 

That’s not much to go on !! More info please, or are you just saying ?

I think it's sorted now something about the vistatherm????