Hi, welcome to jA.
Thanks for the information...the shop you took it to, may not be fully equipped to access the Powertrain computer on this vehicle. If the lamp has illumianted than the vehicle's computer has stored diagnostic information which pinpoints the circuit which has failed. Otherwise it is just a guessing game. The symptoms you describe are common to an internal transmission fault, this normally sets transmission codes so most generic shops cannot retrieve them. Check the level of the transmission fluid, if it's good...you'll need to take the vehicle down to a shop where the codes can be gathered. If you can post those codes here, I can give you a much more firm reason why the problem is occuring.