Since you are already on an established payment plan with the IRS, what you will need to do is request a modification to your current installment agreement. According to the IRS Installment Agreement
Request instructions, "After an installment agreement is approved,
you may submit a request to modify or terminate an
installment agreement. You may modify your payment
amount or due date by going to IRS.gov and entering
“Online Payment Agreement” in the “Search” box. You
may also call 1-800-829-1040 to modify or terminate your
agreement."
With regards to the IRS enforced collection actions that you are referring to, please refer to the Link below for more information as it depends on a number of factors: https://www.irs.gov/individuals/payment-plans-installment-agreements
