We can no longer take client tax payments to a CRA office in Ottawa and have them processed on that day. Instead a payment dropped off at a CRA office in Ottawa is mailed by them to a processing centre in Shawinigan, QC. This can add weeks to the payment being credited appropriately to your account.
For this reason, we suggest you set up a payment account with CRA using their MyAccount system. You can set one up by visiting the Payments to Canada Revenue Agency page.