18 months after porting to Plusnet, receiving letters stating number will be disconnected by Orange

[#1]

Back at the end of 2016 / early 2017, I ported all of my family's numbers from various providers to Plusnet.

My mum, previously with Orange (EE), has now received two letters from Orange stating her number will soon be disconnected from their network, because it hasn't been active for over 8 months. In reality, it was ported away from them over 18 months ago and has been in regular use on the Plusnet network ever since.

I'll be giving Orange a call tomorrow, but I was wondering if anyone else has received one of these letters, and if so, what the outcome was? I'm worried that due to the fact Plusnet piggybacks on the EE network, Orange (EE) may end up disconnecting the number from EE altogether!

I've attached redacted copies of both letters for anyone who's interested.

[#2]

So I just phoned Orange, and it seems there was some confusion over the telephone number reported. It turns out the account they have on their system is actually for a much older number, and not the one ported to Plusnet. So all good, and no action required.