We have had a few problems with ATMs and Nationwide cards recently. My wife's card was retained because they had issued a faulty new card just before we left the UK and the re-issued card was, of course, sent to our UK address. We had it couriered here (great service 2 days for £20 for a well stuffed A4 size letter) and sorted that out. Then my card was blocked twice. I phoned them and got it cleared. It was caused by the high level of activity. We have been withdrawing 20,000 pesos a day recently as our niece is seriously ill and has to have a second brain operation. The hospitals only accept cash! I have found machines which will give 20,000 in one hit, whilst most will now give 10,000. With Nationwide that is not an issue because they make no charge per withdrawal.
By the way I use Skype to call the UK and have found it most useful. I can call any UK landline for an unlimited time for a charge of around £4.50 per month. This enable me to call my business every day, stay in touch with family and sort out problems such as the Nationwide one. The line is super clear. I have even found a website on which you can convert 0891 type numbers to regular ones so can call them too. Finally some credit to Nationwide. They claim a 24 hour, 365 days a year service. I called them at 5.30 am UK time on Christmas day and was answered promptly and efficiently by a bright young lady who was not at all miffed at working such a rotten shift.