The official site labels the DHS processing fee nonrefundable. Do not extrapolate that statement into a complete account of every possible refund or withdrawal consequence.
Ask before committing
Confirm the current terms for the exact payment and any proposed adviser charge. Keep the government gift distinct from a refundable deposit or an investment expected to return principal. Questions about an erroneous transfer or a changed application should be addressed using the applicable official instructions and professional advice.
Ask which amounts are nonrefundable before committing to any of them rather than assuming a general position, since terms vary between components and between stages. Put the question specifically for each: what happens to this amount if the applicant withdraws, if the application is unsuccessful, if the programme's terms change, or if a family member does not proceed. Obtain the answer from the official materials for anything the programme sets, and from the engagement terms for anything an adviser charges.
Record where each answer came from. Where an amount is nonrefundable, that is not necessarily a reason to avoid it, but it should be a conscious decision made with the position understood rather than discovered afterwards when the question has become urgent. Ask, for each nonrefundable amount, at what precise moment it becomes nonrefundable, since the answer is frequently a step earlier than applicants assume and it identifies the last point at which withdrawing costs nothing.