Just about to exchange, seller keeping quiet

[dante]

Four weeks ago we received all the paperwork from the solicitor, agreed to it and sent over the ?32,000 deposit, thinking that we'd be exchanging in days. The estate agent thought this too. Then everything went quiet and it turns out that the seller can't move in with the friends as he'd planned. He has a dog and works from home the estate agent said that he has to find somewhere to rent but is having problems because of the dog. One other thing that isn't helping me be calm is the house next door but one has just come on the market at ?105k above what we're paying. We're buying a dump and this other one is all decorated and has a loft conversion plus a few walls knocked down and put up but no extension and it is a mid terraced and ours is an end.

We were really hassled at the beginning and moved as fast as possible to get things to this stage and now the seller has just gone quite. My building insurance has kicked in, I'm losing about ?100 per month of interest on deposit sitting in solicitors account, and I?m worried that the seller is having second thoughts. I?ve said that we should exchange and have a longer time before completion but don?t know if things can still go wrong after that.
Thanks
Dante