Sorry, original comment not relevant (re: capping overspend) as you have switched to unlimited instead (and both have a delayed start to the next billing date) :-[ :-[ :-[
Plusnet FTTC (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link Archer VR600 modem-router.