This is a question about planning permission. Is it possible

This is a question about planning permission.
Is it possible to have 2 lots of permission, 1 for some buildings to be used as a workshop,
and the other for the same buildings to be used for residential use, running at the same time ?
I will try to explain. There is a workshop at the bottom of my garden on a small parcel of land which runs across the bottom of my garden and that of my neighbours ( 5 houses ) in total. Its about 25m long x 10m wide. Planning permission was granted on 01.04.1993 for the buildings to be used as a workshop for the restoration of antiques, we are told for the whole site. At one end there is an old 2 story stable block which was used as a workshop until about 6 years ago, the workshop then moved into a block of 4 garages which are also on the site. On 16.07.2002 planning permission was granted for the conversion and extension of the buildings for use as a dwelling, with a small workshop. (which could only be used for private use) In march 2007 work started on the old stable, but only foundations and a concrete floor were done. Building control tell us that they made 5 visits and that was enough to satisfy the 2002 permission which said work must start within 5 years. We had a number of issues with the workshop, and were all pleased when the site was going to be a dwelling but sadly that has not happened. The issues with the workshop remain. We have talked to the planning officer and he tells us they have both lots of permission on the site, and there is nothing we can do. I have volunteered to try and get an answer from some one who is independent.

many thanks in anticipation.
martin.