Builder's vehicle parking on double yellow line, blocking my business

We have noticed a van that has been consistently parked outside the garden entrance of 20 Brooker Street, which appears to be obstructing both the parking area and the public view of our business, located at 22b Brooker Place, BN33ZN. We have attempted to address this matter directly with the individuals involved, but they have unfortunately declined to move their vehicle to a legally permissible location. We would be grateful if you could send someone to assist in resolving this issue.