The Court doesn't appoint the bailiffs,that is done by the person/company who you had the original debt with.
They "sell" the debt to the debt collection agency,and the agency pays them the amount(in your case £140.,less a fee,say 10% to 25%)
As the court has given judgement already in this case,I don't think it can go back again(I may be wrong,I hope for your sake that I am).
I don't think a debt collection agency is allowed to harrass you like this,but quite how you stop them I don't know.
Sadly,if you do not pay back the sum now owing,they do have the right to seize any goods from you,but not force entry to do so.
However,if you do not repay the £425.00 (in cash,or goods) it will accrue more charges and so on.
I hope someone with more legal knowledge tham I can advise you,but it had better be quick as this money is mounting up.