As you may know the National Archives received just over 9 million service records from the MOD covering the period 1920 to 1963. They are slowly going through these and cataloguing them. Then, for the records of men born over 100 years ago, Ancestry have a contract to digitise these records. The problem is that the records are stored on a number of pallets, which although they are in a certain order, only the MOD knows the actual order.
It would have been better to initially direct your request to the MOD as they would have given you an unique reference number which you could then give to TNA to identify the pallet and group where the record you are interested in resides. I suspect that TNA are reluctant go on fishing expeditions into unopened pallets at random, to look for a particular record, hence the delay.
I know this doesn't help with when you can expect your requested record, but it perhaps explains, in part, why there has been a delay.
If it's any consolation, I applied for a relative's Canadian Air Force records from the Library and Archives of Canada in August 2019 and finally received them in July 2023.
