Check your online statement. If you see (under DESCRIPTION) CARD RENEWAL or CARD CRITERIA HAVE BEEN FULLFILLED, this means (IMHO) anything credited after this entry goes to the new period.

Also... we all know how wonderful TK IT systems are. The expiry date on the online statement might not match this in TK internal M&S system (my online statements shows 31 August 2017, but in the M&S system it is 3 September 2017 - as confirmed the other day by the Card Pick-up Point agent). Go figure...