Do you have a dog by any chance? For a while I was getting up in the morning and finding the fridge lying open, nothing missing mind you as the fridge is on top of the freezer and the goodies to high up But his detrmination was such that he would get on his hind legs and somehow nose the door open and at least dream on!
I ended up having to reverse the door to stop him.
Short term while a fault is discoverd why not tip it back by proping something under the front feet to allow gravity to keep it more closed ... but only slightly to ensure the compressor/s are able to function correctly ...
Unsure if you can still buy them, but a few years ago child proof fridge locks were available, just a latching piece of plastic. That may help until it's sorted out. Mothercare or similar probably have them.
Check your door seal if it is not drawing slightly in when you shut the doo then it must be punctured or split. If it is old then the seal may be hard. take pingu748's advice snd if you make it the turn of the bead on a level you will do no harm. What kind of Frig. Eng. is it you have, would have thought he could have at least recommended a new seal !
make sure the drain hole at the back is clear. also make sure the salad trays in the bottom are pushed fully in.
the check the seal is ok. check it when the door is shut making sure it is flat all the way round and not folded over anywhere (especially on the hinge side. )