We used See Sri Lanka Tours for a one way trip from Sigirya to Kandy. Our driver was Sanjeewa and we had an excellent experience.
Sanjeewa was very knowledgeable and keen to show us parts of Sri Lanka we may have missed without him as a guide.
The vehicle was very clean, air conditioned and spacious (enough room for a comfortable nap after a lot of travelling).
Chaminda, who organised our trip, was also very helpful and responsive.
Overall, would highly recommend for a great service and reasonable rates.