S P Tax Services Tax filing error and did not take responsibility of their mistake they made. Jersey City New Jersey

Dear Sir/Madam,
I would like to register a complaint against the business below. It is a Tax Services company provides tax filing services to its clients. They have multiple locations and I do not know which one is their head office. I have listed their locations and contact details below,

S P Tax Services

148 Neptune Ave, Jersey City, NJ 07305
1224 John F Kennedy Blvd W, Bayonne, NJ 07002
789 Newark Ave, Jersey City, NJ 07306

Phone: 201-484-7455
Phone: 201-324-0030
Phone: 551-200-9680
Fax: 201-221-8014
Email: sudhirtax@gmail.com

S P Tax services prepared and filed my IT tax return in March 2011 for the financial year of 2010. I had three W2 forms to be used to file IT returns for Federal, Pennsylvania State and Delaware State. They made a serious mistake while filing Delaware State return and they forgot to include one of the W2 into it. Later Delaware State somehow caught this error and contact me in February 2014 with an invoice of due taxes with penalty and Interest.

I called S P Tax services office, sent them my original Tax return of 2010 prepared by their office and also the letter/invoice received from Delaware State Revenue department. I requested them to look into the matter and guide me with the next step. But S P Services did not take any action and did not offer me any help. I called them multiple times and every time different person picked up my calls. Their names were Manya Sharma, Ravi, Kartik. Few of them refused to give me their names. I have sent an email to the owner but he did not reply me either. Finally I contacted Delaware Revenue Department, understood the issue and paid the due tax with penalty and interest in the total amount of $178.65. After that again I called S P services office and notified them that the error was made by their office and they should be responsible for interest and penalty. S P Services clearly deny to take the responsibility of the error they made and they said this kind of errors are common while filing tax returns in their offices and customer is responsible for any consequences. Hence they won’t reimburse money or won’t offer any help because they have lots of work for other clients to keep themselves busy with. I asked their office employee to connect me to the business owner but he refused my request. I asked them to send me a written explanation of why they can’t take the responsibility of the mistake they made but that request was refused too.
 
I personally feel that my consumer rights were not respected by S P Tax services. I do not know if I have any legal background here or if your office can help me with this issue but I am sending this complaint to you to bring one bad business practice to your notice and to see if you have any help/guidance to offer me.

Please feel free to contact me if you have any question or comment.

Thank you in advance!