How to cancel B3 B4 Restrictions in Title Deed

Hello, I am in the process of selling my house and a search by my purchaser’s solicitor identified Restrictions to B3 and B4 in the title deed -EGL524401. 
Background: In 1991 I bought 50% of a newbuild, staircased to 60% in 2005 then bought the remaining share in 2007. All communications confirm that I am the freeholder in the property. In a meeting with my conveyancer in 2007 he mentioned that there is a 3 month restriction not to sell without the permission of East Homes who I bought the property from at the time.

I am not a conveyancer and over the years, it never occurred to me that said restriction would not automatically be spent. I also suspect that there might have been an error in the registration of the property in 2007. Anyway, my purchaser’s solicitor is requesting a Compliance certificate from East Homes which no longer exists. They appear to have been taken over by L&Q , who when contacted state that there is nothing in their records relating to the property and that they have no interest in it.
I am looking for a solution to this issue so that the sale of my house doesn't get affected. Everything was going well before now. All research shows that this is a job for my conveyancer who appears passive aggressive and keeps insisting that I should provide contact information. It has been 17 years, organisations have changed, people have moved on etc. Can I apply for cancellation of said restrictions, by completing RX3 form myself as my conveyancer appears incapable of providing professional advise. Any advise will be appreciated.

Hello Shirley - you can apply at any time to cancel the restrictions using forms RX3 plus supporting evidence as appropriate - see section 3.7.3 of our PG 19 for guidance 
Practice guide 19: notices, restrictions and the protection of third-party interests in the register - GOV.UK

Dear Adam,

Thank you for your swift reply. I have read through the link provided and it appears that I have to upload documents. I assume said documents will have to substantiate my request for cancellation. However, the only document I have is the title deed which contain said restrictions (no time limit). I also have a few lines  in a letter from the conveyancer 17years ago alluding to the fact that the restrictions are for 3 months and  an email from L&Q stating they have nothing in their records and have no interest in the property. Will these suffice? If not, what are my options? Thanks in advance.
Shirley

Dear Shirley - it's a postal application if you are applying on your own behalf. We can't tell you what will 'suffice' as that is got you to establish in law hence the need to seek legal advice as appropriate.
The registered information is something we already hold and simply confirms that the protected interest(s) exist and how they have been protected by way of two restrictions
If it were me I would start by reading the actual terms of the Transfer (see restriction wording) that created the interests to understand how they were created and perhaps crucially how they come to an end be that through time expiry for example and how that might happen/be extended etc.