Removal of possible erroneous restriction

I am currently selling my house and there is a restriction on the title. When I signed the TP1 when I bought the new build property, no such restriction was mentioned in the documents

The restriction was added to the title between exchange of contracts and completion and mentions "clause 9.1 of a Deed of Grant dated 12 March 2019". We did not even reserve the property for purchase until April 2019, therefore I strongly suspect it was not correctly dealt with by the developer before the property was sold to us as we had no interest in the property on 12 March 2019. 

My solicitor has tried to contact the company that holds the restriction but is struggling to get a response. 

My question is - is there any way to tell if this restriction was left on the title in error? or if it was not removed properly? I know that we can get it removed if the restriction holder gives consent, but is there a way to proceed without this as it is proving to be very difficult (nearly 3 months with no resolution)

The restriction is listed at Section B: Proprietorship Register, Entry 4 on Title: BD33093

Thanks, Rebecca 

Rebecca - can you check the title number for me please as that's not the right one as no entry B4/no restriction of the type you refer to

My apologies, it is BD330933

Thanks for speedy reply 

Rebecca - many thanks and no apology necessary.
Such restrictions are carried forward from the developer's/seller's title as and when the new build/plot transfer is registered unless an application is made to cancel same. If there was an 'error' at the time of your purchase it may have been a conveyancing one as they obtained the certificate of compliance needed to complete the transaction but did not consider/apply for cancellation of the restriction thus preventing it from being brought forward to your new title. The conveyancer who acted for you ate time would be the one to ask that Q of though.
5 years on from your purchase it might be quicker to ask your current conveyancer to investigate having the restriction cancelled/disapplied as appropriate depending on the interest it protects and the beneficiary's current position
 

Thank you very much. 

I have raised this with my current conveyancer to see if they can progress getting it removed, and I have managed to speak with the restriction holder and they are looking into it. 

I have contacted my previous conveyancer for good measure to look into what happened with the certificate 

So covering all bases! 

Thank you again