Baby car seat, seat belt help

[ninja.turtle007]

We have a BW's 3 point seat belt in the rear of our caravelle and a Maxicosi cabrio rear facing car seat. The problem I have is the seat belt anchor strap is too long which means the car seat does not fit properly. Is there a safe way of shortening or making the strap adjustable? Or is there somewhere I can buy an adjustable strap/black and red clicky thing?

Any help much appreciated.

[pauly8888]

In my bus, I have a total of 4 different seat belt anchors. I have a mixture of 'belt' type and 'solid wire' types. They are all different lengths, so I'm sure if you looked around you could find the strap you need.