Interior work is delayed and not resuming

Interior work in my flat was started on 12th December 2019 and expected due date for the completion of work was 12th Feb 2020. However it got delayed till 20th March and after that lock down started and now when interior work is relaxed after lock down, still it is not resumed. We have to move out of the rented apartment so need to get the work done as soon as possible but company is saying that they don't have worker now and they can't resume the work. We have already made 80% payment and asking the company to allow us to resume the work with other company in case they are not in a situation to start the work but they are not allowing us to do the same. As soon as there was relaxation in lock down for interior work we had a conversation on phone and asked the company to resume the work but they denied. We have dropped an email and on email also they are saying we can't resume the work. Please suggest what i can do now. In case I ask another company to complete the work, what are the legal issues i have to face.