Advice Please - BRP not at Post Office

I am on the Tier 5 visa and recently arrived in the UK. I went to pick up my BRP at the nominated Post Office on my UKVI letter but it is not there. I have been checking the last couple days and it hasn't turned up.

I contacted UK Immigration and they claim the Post Office has already sent to back to them. It doesn't make sense since it should have been held at the Post Office for another month.

What do I do? Had anyone had this issue before?

What date did you ENTER the UK

What date does your temporary visa vignette expire

5th July. My UKVI letter said mu BRP would be ready for collection from the 2nd July.

I have reported it on the UK Immigration website but they take 5bd to respond.

What was the visa start and end date on your 30 day vignette?

The start and end dates are the 25th June 18 until the 25th July 18.