Been spending a lot of time on here!
Lab's in the US and I'm in the UK, so too much cost in getting negatives sent back everytime. That's what I was thinking, don't know how I wouldn't have noticed a strap in the frame; especially for several shots in a row. The viewfinder's dark, but not that dark!
Send them to Peak Imaging, not sure why you are sending to US because there are far more and better labs in UK
Thanks everyone for the replies. I've checked the settings with the lab and the aperture and shutter speed were fine. They think it may be the shutter sticking at high speeds.
Get your negatives back and kick them into touch, i can take my colour film in go for a coffee then go back and pick them up