If the first name is completely incorrect there could be a chance that this is not the correct result. Again, only a phone call can confirm this.
When my ds2 sat the Birmingham exam a few years ago, and they were about to start the paper after the break, he realised when asked to check the front, that he did not have the correct paper.
The surname was the same and the first name was very similar to his but it wasn't his. Fortunately at the same time, the other boy realised he had my son's paper and the invigilator swapped them before the test started. Fortunately they're both now at KECH anyway
I think this is one of the pitfalls of putting children in alphabetical order as for relatively common surnames there could be a number of children together and there is even the risk of having children with exactly the same first name and surname in the same room.