I can appreciate your position financially and never intended to sound arrogant. God forbid. But the hard fact is that you have been let down badly by your installer. I always feel a moral responsibilty to help anyone I have installed a boiler for and often will turn out free of charge to maintain my reputation locally.
Getting back to your op, when is it overheating? on hot water? on heating or both?
What is the pressure gauge reading when the fault occurs? I feel that ravenheat should be helping you more as well. Have you tried explaining your personal situation to them about your 'absent' installer?
Post back with more detailed fault info. I a not a ravenheat expert but with more info others on here my be able to help more
Getting back to your op, when is it overheating? on hot water? on heating or both?
What is the pressure gauge reading when the fault occurs? I feel that ravenheat should be helping you more as well. Have you tried explaining your personal situation to them about your 'absent' installer?
Post back with more detailed fault info. I a not a ravenheat expert but with more info others on here my be able to help more