You right. Meeting the terms of contract with a mutual agreement has always been a requirement. Who knows what the terms were in their contract but ‘a van’ as the secure storage and ‘I don’t know how’ they got in isn’t good enough. You need to know what locks were on the van. When I insured my motorcycle I had to include the model of D lock, as I learned later, relying solely on the bike’s lock isn’t enough because with enough force thieves can yank the handlebars and snap the key lock off the forks. Or carry the while thing onto a bed