Z_M - I agree with most of what you say. Some of the 'system' is rubbish, some of it works. I've tried to change some of the system from the inside, but it's bigger than me. The working blues uniform is utter bobbins and has been since before I got into the RAF. Part of the problem is the RAF Board (who make the decisions on such things) changing their minds every few years. Changing contractors is a reflection of industry more than it is a reflection of the RAF - cost and directives drive us to the lowest cost and the shrinking budget means more effort is diverted to operational clothing.
The lack of manning is reflected in the service you are getting. More pressure will be on the support of the flying, so effort is shifted there and clothing/barrack sucks from the hind teat once more. Speak to the Supply management on unit if there is a problem.
I can't understand the sizing system to this day. If I want a waterproof jacket 'outside', the shop may well have XS to XL and, if I'm lucky, XXL. I'll probably get one to fit. Not the RAF. About 78 different sizes and nothing to fit a tall human being!
Tailoring - we're chasing a dying specialization there - we need to get a bit more 21st Century on that and make it easier to source to give quicker turnaround. Some poor contracts written there.
I work in DE&S and face the same issues you do - I see several ranks up from me facing the same issues and that isn't exactly filling me with hope. Some things really are too big to change other than at a glacial pace.