I've no idea what Provision 28 is. But it would seem to me that you need to contact them by telephone, which you've done.
More importantly please keep a log of all your phone calls and who you spoke to. In addition, I would write them a letter informing them that you responded to his letter by phone call on x date. Please send this letter with proof of posting, which I think is free with An post.
Keep everything in date order in a binder.
I wouldn't hold out much hope on the Ombudsman, those that eventually go that route, and that would only be a tiny percentage of those that have the energy for that long road, well you've only a one in 10 chance of success.