Why has my switch been blocked?
Blocked switches are actually quite rare but when they do occur they can be frustrating. We cannot overturn a blocked switch so you should contact your old supplier as soon as possible.
The reason for blocking a switch is almost always due to a debt on the account. Your old supplier has the right to block your switch if you have an outstanding debt on your account for more than 28 days and usually they will still allow customers with small debts to switch and add this to the closing bill.
To have the block lifted you will need to contact your old energy supplier to pay off any debts and they will remove the objection and your switch should automatically resume.