How can i fix the coil attachment problem please?

Are you sure you've not stripped the threads in the bolt holes?

Depending on how the thing is put together you may be able to just use long bolts and nuts on the other side.

Alternatively (1), you may be able to drill out and re-tap the holes for a larger bolt.

Alternatively (2) You may be able to get the holes "Helicoiled", rebuilding the thread and allowing the existing bolts to be re-used.

However, given that you are effectively asking "where can I buy bolts" I don't hold out much hope for your ability to achieve much.

XXX
April 2016

Yes you can buy longer bolts - go to a hardware shop in your locality - take the bolts you have with you.

Good Luck...
April 2016