Under UK regulations one cannot report for duty before 0600 local (after a local night off), are the times quoted GMT or local as if they are local then the 7th & 13th are NOT days off.
If a crew member loses a day off then the roster must maintain legality, i.e. 2 consecutive days off within 14 days, if the crew member does not receive these days off, for whatever reason, then it is illegal.