continental finance I made a payment that was not deducted from my account. They hit my credit score by 100 points after I worked so hard to build. Nationwide

I made a payment two weeks ago, 70 dollars which I thought was a bit too high to begin with, and realized they had not withdrawn last months payment and hit me with a late charge! To top it off they didn't wothdraw the 70 and hit me again! my credit score was a 670 and now has dropped to 548 after hard work. They destroyed my credit! I made he payments, verified the bank info, and have called the company. They insist I haven't made the payment when o poated the payment weeks ago. This is absurd.