|So as it seems to me, your line speed is:|
Download: 768 kbit/s
Upload: 64 kbit/s
This might be the problem on using Skype for calls and even more video conferencing.
If the line at Vodafone (768/64) is what you pay for, it's not enough.
If the line speed at Vodafone should be higher, check the contract, you have to call Vodafone, to inform them about an failure on the line.
The original poster should always write the last response !!!
Let us know, if the problem is solved !!!