For the sake of an answer, since OP has mentioned if you move your comment as an answer I’ll accept.
To quote @AakashM‘s Comment in full:
Have a look at their website to see what their constituency contact arrangements are, they may want a phone call, but basically yes just tell them your problem and they may be able to help (at least with the ‘this government department is not resplying to me’ bit). You can use theyworkforyou.com to find out who your MP is, if you don’t know
Credit:stackoverflow.com‘