There will be no quick and easy solution. Many local councils declare parking spaces close to shopping centres and transport hubs as ‘resident only’ beyond one or two hours. Is there scope for a local campaign? It would have to be considered by the council, and there would be a lengthy time for notice to be given and objections to be called for. If your efforts were successful, you would have to pay for a permit, and there is no guarantee of being able to park, but it would be better than nothing.
You did not mention how many visitor spaces your building has. Many schemes are ready to tolerate occasional and brief occupation of a visitor space, but twice in one week seems provocative, especially if it was the ‘last space’ on each occasion and you gave the impression that you had decided to base your car there.