H&R Block

I have been filing my taxes with H&R Block for almost fifteen years. Recently, I received a letter from the IRS on May 5^th 2014, stating that I owed them a sum of five thousand dollars, which is really going to put my family in a financial hardship. After reviewing the letter the IRS sent, I was prompted to review my 2012 tax return.
Upon reviewing my return, I realized that the tax «professional» who filed my 2012 return failed to include two W2’s. These W2’s were provided to H&R Block upon filing the return and are actually stapled within the completion packet they provided to me. I called the H&R Block’s customer service number on May 7^th, 2014 and spoke with a customer service representative who advised me that the best way to handle this would be to go into one of their local offices and have them review my return as well as submit an error claim for the 2012 filing. I was reassured that even though I did not purchase the H&R Block «Piece of Mind» Guarantee, that their basic service guarantee would cover my situation as the error was made by the «Tax Professional» at H&R Block. At the very least, the H&R Block Customer Service representative claimed that H&R Block would pay my tax penalties and interest.
Several days after scheduling the appointment, I received a phone call from one of their local offices advising me that the appointment that was originally scheduled was scheduled with a closed office and that they office I should go to instead is the one located at 11 015 S. Harlem in Worth.
About a week after that, I went into the office and conducted my appointment with «Senior Tax Professional» by the name of Rita McGuire. I provided her with my paperwork for review and asked her several questions as to how to go about dealing with the IRS since I have never owed them any money and never have been in this situation before. Rita was very frustrated with me, and said that it was my fault for not properly reviewing the paperwork. Every year I drop my taxes off, they get filed and I come back in to sign the documents. Nothing is reviewed or explained the whole process takes about fifteen minutes. Also, every year I usually receive a substantial refund anywhere from $ 3500-​$ 5000 so I believed that all was in order. I then asked her (for the fifth time) what I should do about reaching out to the IRS, when she could not answer the statement; I stated that the IRS expected to receive a full payment from me by June 4^th, 2014. Rita Mc Guire, the «Senior Tax Professional» at H&R Block in front of my husband and one of her co-​workers got very loud and rudely exclaimed to me, «What did you think that you were going to come in here and we were going to cut you a check for five thousand dollars?» At this point, I felt defeated, humiliated, and very emotionally stressed. I collected my paperwork and decided to leave her office as I do not feel this is how you should treat a fifteen year customer when your agency created the error.
I called their customer service number again and was told by a woman by the name of Sharon that the Regional Manager was involved and would be giving me a call. June 4^th has come and gone, I have not received any phone call from anyone at H&R Block, they are not honoring their basic guarantee, and now I’m left to sort this problem out by myself with the IRS and assume the five thousand dollar tax debt that H&R Block has created for me by incorrectly preparing my 2012 return.
Here is their guarantee posted online on their company website.
How am I supposed to file a claim, amended taxes, when not one person will return my phone call and when I went into their offices to file a claim, I was treated like a piece of garbage and verbally abused?