Service Records application - MOD response timescale

Asking for advice, I sent my request with a dated cheque 5 months ago.
How is it best to contact them to to replace with an updated cheque ? as I do not want to lose my place in the queue and go to the back of it !
I have already tracked down most of my grandad's movements myself through family records, army discharge papers and Kew but have an important missing period of Mar to Nov 1944 (probable attachment) !

 

Thanks very much Owen.
FYI - for others, I sent an e-mail and got the following prompt reply.

The disclosures team department has been closed since 20th March. Some are at home working on laptops.
I sent in my application mid April so it has not yet been opened.
So I guess I'll be hoping to get the details in 2021.

Fortunately my grandad left many clues and I have pieced together much through photos, release book, war diaries so at least I have a good idea of most of his movements just one part missing

 

Finally got my father's records! It must be over a year ... Very sketchy. But I have heard from others that RAMC officers' records are very thin. Strange ... My mother was a naval nurse and the record the RN sent (very rapidly) was incredibly detailed including references, vaccination records, pay records and regular staff appraisal documents. Just a few letters in my Dad's, mainly about his release from the Army. Kate

 

Latest from MOD in Glasgow (they mailed me this) - many of the team have now returned to work.
There are approx 10k waiting to be opened. There was a backlog of 6 months of ongoing enquires when they closed.
If your cheque is now out of date they will be in touch and you will not lose your place in the queue. I'm looking for this info to track my grandad's involvement in the Mulberry B as he was a Royal Engineer, barge engineer at Marchwood in 1944.

On a brighter note my family received notification today from the medal office that we are to receive the Burma Star that we applied for to recognise my grandad's service in 1945.