Update on current situation re time lag with HMRC and paying back NICs. Found this on a very well known UK website forum, thought it might help people like me on here. My husbands application was sent by Track&Trace at end of October, they received it early November. Looks like there is at least a 22 weeks wait for a letter, but they will honour the application.
Just a heads up for anyone contacting HMRC over VNICs before the April 5th transitional period deadline ( I finally got through after a 50 minute wait - not great when ringing from abroad ) the Computer Says No drone who finally answered says there's a 22-week delay before any letters are answered but that if they're received before the deadline you will still be able to pay.
22 weeks...
Unbelievable.