I honestly didn't realise about the nexen change until today as it was lashing it down when I picked up the car and there were other things I wanted to check were done.
I wasn't that happy about the Nexens let alone these. but tried negotiating on it and as you said they weren't interested, implying that someone with noncwr knowledge would buy it anyway.
Also tricky as I had already put deposit down to secure the car. ( As it's colour I wanted)
The only other car close was an additional £2k.. and ironically had also not great tyres on.
Will find out for purpose of thread what they are and report back !
Edit:
Tracmax X Privilo TX3 on a local 22k on the clock 2018 Mustang £30,500.
I guess I should feel good... My Triangle effexsport are an extra £15 per corner.... So must be better...