First and foremost, plz edit(modify) your post and remove sensitive information like your name, file number, and e-mail from your post.
Second, i know how it feels to receive that e-mail as i have been there myself, so what you should do is:
1.email cic at LDNIMMIGRATION @ international.gc.ca (by pressing reply on their e-mail ) and place URGENT on the front of subject line(do not change subject)
2. Explain the situation calmly and confidently and provide the TCS Tracking number(shipment number) that you have on the receipt (do no upload that image of the reciept as it will cause problem when u are sending the e-mail)
3. Mention in the e-mail that to be sure that cic london receive your docs this time, you are sending it again through DHL (use DHL this time)
4. Prepare your docs, and write a detailed (try not to be rude to cic at any point) cover letter explaining your situation and thanking them that they gave you a second chance to meet the deadline.
4. prepare and finalize your docs ASAP and send them on :
Postal Address: NEW
High Commission of Canada
Immigration Section
Canada House
Trafalgar Square
London SW1Y 5BJ
United Kingdom
Good luck and PM me if you have any more questions.
Regards,
Zam