Prevent users from using locations other than the auto-suggested options

When searching for listings, we discovered that typing “London” directly in the location (snear field) and not choosing any of the auto-suggestion returns the wrong results that include listings outside London.

The only way to return the correct listings, is by choosing the auto-suggested option of “London (City)”. Is there a way to force users to use only the auto-suggested locations or if they do not choose any, then force the location field to use the first option in the auto-suggestion. Otherwise, we expect a lot of users will be seeing listings outside the locations they intend to search.