Outward call delay and overall choppy connection.

Hi all,
I live in London and just recently changed to lebara from ee.

I have noticed that when I try and make a call it takes very long before it actually starts to ring.
i have also noticed that the connection is really choppy. When I speak a lot of times they can’t hear me or when they speak I can’t hear them.
obviously this is really frustrating. Is anyone else experiencing this problem?