Desert in my car's engine

I have had my vehicle serviced at this branch many times before and always trusted them to assist. My vehicle was sent in for replacement of the water pump and timing belt. I contacted the service agent late afternoon on the day my vehicle went in and was told that they wanted to keep it another day to bleed the water system and to ensure that all was fine. The phoned me late morning the following day to let me know that my vehicle was ready for collection. Not only was it handed back to me full of oil smudges on the bonnet (it was cleaned on premises) but the following morning on my way to work (quite a distance from home) my car's temperature gauge showed that it was overheating. Eventually I had to get assistance at a garage on my way to work. There was very little coolant in the radiator and when I took it back to them the afternoon I was told that they definitely checked the coolant levels the day before. They tested to ensure that there was no permanent damage to the engine. I feel cheated and disappointed with the service received.