if purchase from the purchases daybook have been credited to sales and dealt with correctly in the payables control account. This would cause the suspense account to be created, right? The correct entry should Dr. Purchases and Cr:Payables, correct?
What should have happened is: debit purchases; credit payables.
What they have done is: credit sales; credit payables.
Therefore there is no problem with the payables account.
The correcting entry is:
debit sales (to remove the wrong entry) debit purchases (to put the correct entry) credit suspense account (with two times the amount)
I do suggest that you watch my free lectures on this. The lectures are a complete free course for Paper FA (F3) and cover everything needed to be able to pass the exam well.