Engine temperature won't go above 55, no matter how far I drive the car. This is a 1.4 tsi 103 kw Octavia with EA211 engine. At first it only went up to 85 degrees, then only 75, then only 60 and now it doesn't go above 55, in fact, it jumps back to 50 from there. Both thermostats have been replaced, but the problem hasn't gone away. Any ideas?