OSO unvented water heater - element keeps shorting

[windchimes]

Please can anyone advise. In my flat is an OSO water heater and the flat is only 4yrs old built by Linden Homes and everything has gone wrong. My main worry is the heater as a plumber replaced the element in Mar this year , then it went in Nov and Oso said it is due to Limescale. I had another element put in 4 wks ago and that has just gone and I don't know what to do as I can't believe limescale could cause that level of problem.I have to use the boost at the moment to heat the water and that is peak electricity price so am pnretty gutted. Can anybody suggest what the problem could be, my plumber doesn't know and I don't know if it is a faulty install or problem with the electrics ? Any advice and recommendations for help . I am in Slough Berks.
many thanks

 

[tamz]

Get a titanium immersion fitted. They are a bit more expensive but will last a LOT longer.

 

[windchimes]

Thanks. Will investigate.