There are maybe a dozen very different models heater, probably made by a variety of different suppliers, Ann with the Igenix badge stuck on. Which one is it?

You can always contact Igenix directly:

https://www.igenix.co.uk/contact-us/

Sksjge
January 2021

Depends what is wrong with it.

Briefly and concisely, what are the symptoms?

Not a clairvoyant
January 2021