At September 30, 2020, we carried a total debt balance (including accrued interest) of €5,483.0 million, of which €1,393.1 million principal amount is related to the € and USD-denominated Senior Secured Fixed Rate Notes due March 2028 and €3,067.9 million principal amount is owed under our 2020 Amended Senior Credit Facility with maturities ranging from April 2028 through April 2029. Our total debt balance at September 30, 2020 also included a principal amount of €340.3 million related to our vendor financing program and €4.0 million for the outstanding portion of the 2G and 3G mobile spectrum licenses. The remainder primarily represents lease obligations associated with the Interkabel Acquisition and lease liabilities following the adoption of IFRS 16 as of January 1, 2019.
At September 30, 2020, we carried €340.3 million of short-term debt related to our vendor financing program, all of which is maturing within less than twelve months. This represented a decrease of €14.6 million versus December 31, 2019 and a seasonal €25.2 million decline in the third quarter. In line with our full year Adjusted Free Cash Flow outlook, we expect our vendor financing program to ramp up in the fourth quarter. As of end-October 2020, the applicable margin on our future short-dated commitments under the vendor financing program has been reduced by another 15 basis points to 1.95% over EURIBOR floored at 0%. This reduced interest cost comes on top of an equivalent 15 basis points margin reduction in February 2020. Given the aforementioned size of the program, this will have a modest accretive impact on our Adjusted Free Cash Flow in 2021 and beyond.
In the first half of 2020, we finalized several accretive (re)financing transactions including (i) the successful issuance of a new 8.25-year USD 2,295 million Term Loan (“Facility AR”) and a new 9.25-year €1,110 million Term Loan (“Facility AQ”) in January 2020, (ii) the issuance of a new 6.2-year €510.0 million revolving credit facility in April 2020 ("Revolving Credit Facility I") and (iii) the April 2020 10% repurchase of our 3.50% €600.0 million Senior Secured Fixed Rate Notes due March 2028. Compared to June 30, 2020, there were no substantial changes to our debt profile and payment schedules as shown in the table below.
Excluding short-term liabilities related to our vendor financing program, we face no debt maturities prior to the March 2028 with a weighted average maturity of 7.8 years at September 30, 2020. In addition, we also had full access to €555.0 million of undrawn commitments under our revolving credit facilities at September 30, 2020 with certain availabilities up to May 2026.
For more information on our debt instruments and payment schedule at September 30, 2020, we refer to the Q3 2020 Investor & Analyst Toolkit.