You can apply for the bail to be varied in one of two ways.
1. Apply to the magistrates court. If you go, they will guide you through what to do.
2. Apply to any Custody Sergeant at the station where the conditions were imposed. You could just turn up but it would be worth phoning the Custody Suite before hand in order to let them get all the stuff together.
Neither route is guaranteed. All the original representations will be considered, as will anything new that you wish to raise.
They have two options.... keep the same terms of bail or vary the conditions. The conditions can be made more stringent of it is felt necessary... up to the point of actualy cancelling the bail and taking him before the court without bail (although this is unlikely if he is sticking to the original conditions and doesn't put his foot in it by saying he'll do what he likes regardless of the decision).
Either way I would take legal advice first, but if the officer in the case is not getting back to you, go straight to the Custody Sergeant. The decision is made by the custody sergeant, not the OIC, despite what they may tell you.