Firstly, you should start by contacting - email and phone - manchester as its always worth a try.
For remarks, there are different types. For some exam boards you can pay ~£15 for them to check the adding up of the marks which is a rip-off. Otherwise, you can pay ~£40 to get a remark of the paper, but this could potentially drop a mark, but I’d say go for it.
The way it works is, if they have made a mistake and thus correct it, you get your money back.
Good luck