DVR6K. .I saw same deal as you for the LHR-MAD. Check terminal and flight number, because it may be a code share with BA. (T1 BA, T2 IB)
Whilst on the subject of code shares, whilst working in a travel agents, when checking fares, it was worth noting that on code share flights the airlines offer different fares on the same flight. eg bmi and Lufthansa code share on German routes, but we would check both carriers and the airlines offer the same flight but with different fares.