voicemail issues with apple watch/iphone 6s on ee uk

can't access voicemail on iPhone 6s plus when paired to apple watch, my network carrier is ee in the uk, they have been working on the problem for 3 weeks now, but still no answers, seems to be a platform conflict issue, they say, really surprised apple didn't check that the watch would work on the network they chose to appoint as the sole carrier, has anyone any answers, have you experienced the same problem