Radiator query on house survey

[Catred4]

We're selling our house and the buyers want us to reduce the price based on some concerns raised through their survey. One is:

"Landing radiator is not connected to central heating system. Pipework comes through the floor but is not connected and therefore obviously bypassed somewhere. Cost of plumber £250+VAT to source the bypass and reconfigure / connect radiator and test system"

We just don't understand what this means as the radiator works and gets hot, so how can it not be connected to the central heating system?!

Any ideas gratefully received!

Is there any pipe work that comes through the floor but isn’t connected? Maybe left in situ after the system was replaced & surveyor has got confused when typing up the report?

Invite them round to feel the radiator on maybe? although if there are other issues, asking for money off for a £250 (seems steep) plumber, is probably just a tiny part and being listed just to give weight to there are multiple issues (in their opinion) to fix.

Have you told them this?

Ridiculous. Tell them they can come by you will turn on the heat if you must. If it gets hot it's attached and the surveyor is just wrong! What else? If only be looking fur a price reduction if there was something major (like roof was failing/massive dry rot issue etc).

The rad works. There is no issue surely?