Hello Dougmac, and welcome to the forum.
As I am sure you will appreciate problems like yours are most quickly resolved by an experienced person who can check various features of the appliance first hand. Trying to resolve some problems through a forum is often difficult either becasue the symptoms are not correctly understood or reported to us correctly, and we have no way of knowing the competence of the correspondent to undertake investigations or repairs.
Fundamentally no heating means that current is not passing through the elements, the problem is we don't know why that is. it could be:-
A failure in the 230Vac mains supply to the appliance.
The appliance's control circuit may not be transferring the power through to the elements - Could it be you have not followed the instructions to use the appliance correctly?
There will be a number of thermal protection devices which for one or more reasons may have triggered and are preventing the current reaching the elements.
The elements may have failed
If it turns out to be a thermal fuse or over temperature switch, then you need to establish why it may have gone over temperature, and prevent it from happening again. It could be an element has gone faulty and is getting hotter becasue of the fault.
It's far from unknown for some thermal fuses to become more sensitive with age and it may simply have worn out.
Air circulation fans in caravan heating system are notorious for getting clogged with dust. The reduced air flow could have caused the elements to get hotter than is safe.
Those are just some of the possible reasons.
Bearing in mind we are dealing with 230Vac mains power, and that has obvious dangers, if you are competent with a multimeter you could start to trace the power circuits to narrow down where the problem could be. If your not confident then really it's a job for someone who is competent.