Juan.
The MRU flight you mention is currently a bone of contention. The crew did operate home after 1 local night expecting their entitled local night to be credited to them later. At present the company are saying no to. In effect the crew worked home on their day off, and at present are being told they are not entitled to it back on a later roster.
This is the problem with breaking agreements. If you happen to be cabin crew it only works one way. So, should such distrubtion occur again, BA now have another 15 cabin crew who will demand what was agreed originally with the company.