My wife applied for ILR at Sheffield PEO only last Thursday. I'm pleased to say that she was successful. The whole process took about 2 - 2.5 hours.
We applied online for an appointment 6 weeks later. At the time of booking, the full cost of the visa was requested. The wife used her Visa Debit card, no problems.
Make sure you print off the payment sheet and put that at the front of your file. The PEO staff will want to see that before they will proceed with the application. No need to complete the payment section of the application form itself, just make sure the payment sheet is at the front of the file.