Client questionnaire

General information for the business: We are a marketing consultancy & wish to email previous clients a questionnaire about the quality of our service/products
Data to include: We have written the questions which each need a written response rather than a multiple choice selection. We need help putting these into a professional format that's easy for our clients to use. Ideally, we would like the responses to be anonymous so that they can answer more honestly. Free off the peg survey templates like SurveyMonkey look like sales pitches for SurveyMonkey & the upgraded versions that don't are too expensive for a company like ours that may not survey clients again for many years.
Extra notes: We just need the research set up. We will interpret the results ourselves.