If the API responses seem to contain data that do not comply with the parameters used in the endpoint URL, you may try checking the following:
URL parameters are case sensitive
All URL parameters you are using should be in lower case. For example, think of timespan vs Timespan - the API call would ignore Timespan due to the use of the capital T.
Timespan denotes duration
The Timespan parameter represents time intervals, not dates or timestamps. For example, if you wanted to get responses for the last 10 minutes, you should use the timespan:10 parameter (provided that the subject API Service supports timespan in minutes - please check the Documentation page of the respective API Service for valid values).