no heet

could it be a knackered heater matrix, could you have an air blockage. for blockage park facing downhill and empty coolant,then park uphill and fill slowly,when it seems full run engine leaving cap off rad and top up as necessary,squeezing pipes etc. you could try blasting water ways with either powerful hose pipe or airline.

You probably need a new thermostat installed in your radiator. Sometimes they get stuck and won't open, causing you to have no heat.