I have come across this issue with MetaTrader both 4 and 5. The terminal shows incorrect market rates sometimes. Even when we read the rates with the MQL EA the rates are incorrect. This makes trading difficult. Here is an example with screen shot, where the price has moved below the take profit in a sell position and the position still remains open.
When I checked the Journal, I saw that the rates mentioned in the re-quote was much different from what was on the screen or what we could read with the help of an EA. I opened Tradestation(another trading program) and saw that the re-quote rates where same as shown in Tradestation.
Incorrect market rates not only make us miss an opportunity, it can also make us make a wrong trade as indicators depend on the rates available with the terminal. I am not sure where the problem is, is it with the broker or is the problem with the MetaTrader Terminal/Server?
I haven't contacted the broker yet. I wanted to understand where the problem was.