Quick question - replacing openreach modem

[#1]

Quick question, I wont go into why as this is being discussed in other threads currently, but im asking here as I really don't want to ring plusnet support after an awful fuss trying to raise a ticket over the weekend, but if I buy a new HG612 Huawei openreach modem from ebay, is it a case of a straight swap ? or do I have to report serial numbers/modem info to plusnet before I swap it out ?
Sorry if its an obvious question, but I have never had to swap out faulty ISP kit before.
Cheers

[#2]

Plusnet didn't supply the modem - BT Openreach did and Plusnet don't have a record of the serial number etc. so you can just switch it

[#3]

Thanks Oldjim, can be dealing with the harassment that is PlusNet support so will give that a try. Feel free to close, thanks.