Based on the bylaws that govern apartments in Chennai, parking spaces cannot be sold as a separate entity. Car parking and open terraces are supposed to be a society's common area. Parking spaces are not considered a part of the apartment and hence, cannot be sold as a separate entity. Developers can sell parking spaces only if they manage to prove that they have used the FSI (Floor Space Index) allotted to them to develop the parking space. A 2010 Supreme Court ruling mentions that buyers do not have to pay for the purchase of parking space, either open or closed, that is built by the builders.
Through various cases, courts have settled that selling of parking spaces is illegal. Hence any transaction of buying them would be null and void. If your Deed mentions “Common Areas and Facilities”, it is deemed to include parking areas as well, unless it specifically says it does not. This is under The Tamil Nadu Apartment Ownership Act, 1994, and under this Act, each apartment owner is entitled to an undivided interest in the common areas and facilities as specified in the Deed of Apartment. The parentage of the undivided interest of each apartment owner in the common areas as expressed in the Deed of Apartment has a permanent character, and can’t be altered without the consent of all apartment owners. 
Hence, your case will depend largely on what is there in your sale deed. However, you have many remedies. Remedies available:
If the developer is a member of CREDAI, the grievance can be taken up with the CREDAI Chapter in the city having the Customer Redressal Forum to find solution. You can file a complaint online by clicking here
. Once the complaint is received, it is duly filed, serial numbered and sent to the members against whom the complaint has been filed. He then has to respond within a stipulated time from the date of the receipt of the letter. In case the response within the said period is not received, the same is to be brought to the notice of the Grievance Committee for action. The receipt of the comments from the Member, same shall be sent to the complainant. If deemed necessary by the committee, the members of the committee may carry out inspection at the site. If the Complainant is not satisfied by the reply of the Member and if issue is not resolved the committee shall call both the parties for personal hearing and tries to resolve the issue with a suitable order and close the matter.
If your builder is a non CREDAI builder, you can call the National Consumer Helpline (1800-11-4000) or visit the CORE (www.core.nic.in) website. Alternately you can also file a complaint against the unfair practices of the builder before the Competition Commission of India which has been empowered to investigate anti-competitive practices and impose stringent penalties on the offenders. You can learn more about how to file a complaint with CCI by clicking here
. If all fails, the last resort is to file a case in the consumer court.
If in case your case is dismissed in the consumer court, you can approach the High Court and seek redressal. 
Nahalchand Laloochand Pvt. Ltd. v. Panchali Co-operative Housing Society Ltd 
Section 6 of the Act.