I've filed a FOI request to find out what the reason is for the unacceptable delays. Asked them how many people are off sick/furloughed, how many emails they get each day that require a response, the average time between assessment and decision etc.
Next step here is to file a formal complaint, I've already had to file one (due to their refusal to book a consultation manually via phone when their CELLMA system was down for months), that at least gave them a kick up the arse.