Roofing problem?

[Littlebig]

Hi everyone, almost a year ago I completed my first ever property purchase and it was a new build. Overall I am quite happy with the build but of course there have been some issues with the house. It is a semi detached and one of my concerns (not saying issues as I’m not sure if it is actually wrong) is the roof. At the back of the property there is a section in the middle where the roof tiles are elevating - this is right in the middle between the two houses, and one section on the side of the house where the tiles are lifting and looks like they are not sitting in properly. This was reported to the builder as there was a broken tile as well and they came and replaced it pretty quick and also found another one that needed replacing. However when I asked them about the the little “belly” at the back they said its because the wall separating the two houses is too high but once they have been authorised by the builder they will come and sort it out. This was in the beginning of the winter and I told them I don't want any kind of work done on the roof until the summer months. I will chase this up and get to come back soon and sort it but was wondering if someone can tell me if thats actually what the problem or if it’s a problem at all. I looked at the other houses but couldn’t see a similar problem on any of them.

[tonyshouse]

I reckon broken bits of tile stuck in the overlap, could be wind uplift, cement lumps from manufacture stuck to the ridges in the overlap. 

[Littlebig]

1 hour ago, tonyshouse said:

I reckon broken bits of tile stuck in the overlap, could be wind uplift, cement lumps from manufacture stuck to the ridges in the overlap. 

Thanks for the reply. I’ll ask the roofers to check it out and correct it as recent storms make feel a bit anxious considering last time I had someone else's shed in the garden 😂.