Motorhome locksmith

We recently bought our first motorhome (Bessacarr) and have a couple of issues with keys/locks. 

The thetford service locker door has jammed shut and the key won't unlock it and the main habitation door wont lock or unlock from the outside...(they both worked on viewings and collection, I think my other half has been a little heavy-handed!) it will if we jam a flat screwdriver in but obviously this leaves it very prone to break-ins so we'd like both locks replaced. 

I've called normal locksmiths and a caravan repair place and neither could help me. 

Any advice please?