Reliable Shipping Companies in Thailand

I am a small business owner and a foreigner living in Bangkok. I need to ship around 50 packages per month on a regular basis. DHL and FedEx are very expensive — in fact, the shipping cost is higher than the cost of my products. I have tried contacting Thailand Post to set up a business account, but they have not responded to my emails. Additionally, their delivery times are quite long and seem unreliable. Is there anyone local who can recommend a reliable and affordable shipping company, or suggest a better solution? I would really appreciate any help. Thank you 💕