How to recover overremittance

Hey Guys,

In my 2017 payroll year a former acting accountant was tasked to calculate and write the check for payroll remittance to CRA for our business, after he did such, I took over and did the remaining payroll remittance for the remainder of 2017. While I was tasked to do this, I normally go out of my way in any job and go above and beyond my responsibility so I did a quick audit of the books and noticed that where he was suppose to remit a specific amount per month for the employee deductions, He actually did deduct the correct from the employees checks, but in our remittance account he wrote the check to the CRA for a much higher number, so despite that, NO EMPLOYEE WAGES WERE AFFECTED. When it was my turn to remit, I did the calculations and remit the correct amount because I was given the position and only had 2 days to send the remittance. after sending the remittance I did the quick audit of the books and discovered he over contributed to the CRA, I called them and they told me to under contribute for the next period, however the amount he over contributed was equal to the next months contribution plus more, so there was a surplus of like 400 bucks per employee, that is a lot of money so when I filed the return and did the T4, my numbers matched but there was a balance on the account. How do I get this back? with 5 ore more employees this balance adds up significantly and because of this we had to take money out of other accounts to not go in the negatives in our payroll bank account, any ideas? They send me the PIER form and I filled it out and explained why the over payment error occurred but does that guarantee me a refund or not?