You don’t have any other option. If you want a particular work experience to count:
The following documents are mandatory for each work experience declared:
- a reference or experience letter from the employer, which
- should be an official document printed on company letterhead (must include the applicant’s name, the company’s contact information [address, telephone number and email address], and the name, title and signature of the immediate supervisor or personnel officer at the company),
- should indicate all positions held while employed at the company and must include the following details: job title, duties and responsibilities, job status (if current job), dates worked for the company, number of work hours per week and annual salary plus benefits; and
- if the applicant is self-employed, articles of incorporation or other evidence of business ownership, evidence of self-employment income and documentation from third-party individuals indicating the service provided along with payment details (self-declared main duties or affidavits are not acceptable proof of self-employed work experience).
Please search through the forum’s previous posts on work experience letter. You will find recommendations on what to do, including getting unofficial letter from (former) colleagues and proving to CIC that you tried.