I recommend you to design and implement a customer satisfaction survey.
The customer satisfaction survey is a tool that allows you to measure, through a study, the level of conformity (or not) of a customer with respect to a certain service, company or brand.
For this purpose, you may design the survey based on variables and questions (closed and open-ended) validated by experts.
Regarding scales, you may include Likert scales and introduce a Customer Satisfaction Score (CSAT). I also recommend including a Net Promoter Score (NPS), a parameter to predict customer behaviour in terms of loyalty and satisfaction towards the brand.