How to fix muffled/distorted Siri voice

I know this is a very common topic and I apologize if the answer is out there. But, I upgraded both my iPhone and iPad to iOS 7.1 on release day and since I live in the UK, I got the more natural sounding Siri voices in male and female. At first, the voices on both devices seemed pretty muffled and distorted and I was aware of this happening after updates. I Googled how to fix this and found the following tutorial to force it by downloading enhanced voices for VoiceOver.

http://www.neilturner.me.uk/2013/09/20/fix-siris-muffled-quiet-distorted-voice.h tml

I took a few minutes for it to work on my iPad but my phone is still distorted. I gave it a few days because I knew it usually downloads the voices when charging but still nothing.

If anyone knows what's causing this and how to fix it, please let me know!

Thanks in advance,

PS: I remember reading something about it being affected by using VPN (which my phone uses to connect to wifi at work which the iPad has never done. Not sure why this would affect it though...)