The issue you are likely experiencing has already been reported here.
It is not related to your service provider, but to the device itself.
Its solution is in development. At the moment it is set to be included in 7.5 firmware version, however, its release timeframe is not concrete at the moment.
If current performance is not satisfactory and waiting for an update is not suitable for you, return the device to your reseller.
Apologies for the inconveniences.