In reply to james mann:
I had all my camalots done about a year ago - a mix of old and new types. BD are actually very generous about it - all you have to do is post the cams to them, and they re-sling them and post them back with no charge. If I remember correctly, it was about three weeks from posting them out to getting them back.
The hard part was getting them to reply to an email to authorise the work in the first place! Hopefully they've got better about checking their email.