Seed Group Company

Dear Sir, I have been dealing with this company since February 2014 to invoice and pay my salary. The first month my pay was done on time and my full salary as per legal contract was done. I resigned on the 19th June, mainly due to late salary payments after February. I have the proof of actual payment after been told that payment would take 3-4 days. I handed in my client signed time sheets on the 19th June and was told every day that my salary would be paid soon. It is now 20 days later and still no salary. The company above portrays that they run a professional business but little do they realise that salary delays cause issues with a person's finances. They gave me a don't care attitude and once again I got a mail to say that two (2) days of my February salary would be deducted in Junes payments. This is illegal as they broke the contract clause. How can I take them up legally? Many Thanks for your advice and assistance.