increases usually occur because a discount has ended.
You should go to the VM homepage virginmedia.com and lsigninto My Virgin Media. You should then compare your most recent bill with December/January's which will show any changes. If your discounts have ended then i would applying for a package regrade.
You can either send a text with a description of regrade to 07533 051809. Your message will go into a queue and a representative will respond to you as soon as possible. It may take a few days.
Or you can call 150 from your Virgin landline, or 0345 454 1111, butbest to call at 8am to avoid call queues.
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali