So you had a normal ECG with a rate of 100-110. The most likely reason for the reading of 216, given the lack of symptoms, is that the machine, whatever it was, was double counting. Unless a qualified doctor SAW an ECG trace
The next question is what is the rate when you have palpitations? I suspect it is higher than your 'normal' 100. You need a 24 hour ECG to produce a recording of what the palpitations are. A cardiologist can then advise you but often this can be treated by a daycase procedure, and after a period of review other regulators have granted a Class 1
So I would suggest you ask for a '24 hour ECG' which you may need to wear for several days to record a palpitation episode and then get to a cardiologist. You wont get a Class 1 without it and although the commoner cause are totally treatable, just leaving it might carry some risk.