I think I have the wrong B618mine doesn't do 2300mhz
No carrier aggregation on Telkom for you then. In fact you will be limited to 1800MHz only. I doubt you will enjoy that band in Hatfield....
Test it and check but I would not get my hopes up. You want to test 2300MHz and see what that is like might be worse. If it's better then swap the B618 for a B315.