Austrian mobile now blocked on U.K. landline?

[Fearno]

I have been calling my Dads U.K. sky talk landline weekly for 2 years from my Austrian mobile and then 10 days ago every time I rang it just cut out. I have since contacted my mobile provider in Austria and they have informed me it's Sky talk who are blocking the call. I have also tried to call from 4 different mobiles and the same happens. My Dad is elderly and not of best health and looks forward to my calls. Please can someone help me with how to resolve this problem? Ps I don't have a landline to call from.

[Daniel0210]

@Fearno 

Have you other family / friends in the UK who can call your Dad from within the UK and

a) confirm that his landline is working correctly

b) explain to him the problem you're having making contact.

[Fearno]

@Daniel0210  Yes someone in the U.K. has called his landline from their mobile and it goes straight through. 
He is aware of the problem but isn't capable of dealing the problem as he's not well enough.

I think issue sits with Sky Talk?

[Daniel0210]

@Fearno 

Hopefully someone can be with him and help him call Sky (and get through the security questions) so he can report the issue.