Dimplex fireplace heat cuts off.

[psomers]

My 2013 Montana with dimplex model NBDF2608 fireplace has started cutting heat off after about 20 seconds. The fake flames continue but blower and heater quit. Turn unit off for sever al minutes and it will again run for 20 seconds. The unit is out and in middle of floor. It has been disassembled and is clean of all dust. The problem is the over heat sensor mounted on the heating element. The sensor can't be replaced and have to replace heater and fan as unit. Dimplex doesn't have the part and wont have until March with cost of $250. Think of just replacing unit. Unit is 26" x 22 7/8". Has anyone replaced unit and what did you replace with?
PS: part number of fan/heater asm is 2000330100.