By James Rodger & Joseph Wilkes Martin Lewis has issued a stern warning after an eight-word message was received by around 20,000 people. Known for his appearances on TV shows like This Morning, Good Morning Britain and The Martin Lewis Money Show, the financial journalist and BBC Sounds podcast host, expressed his concerns on Twitter. Mr Lewis urged: “Please report ‘sorry we are experiencing unusually high call volumes’ messages. We’ve had 20,000 reports in so far to test if some firms (banks, broadband, mobile, energy, water etc) have this for EVERY call. Pls take 30s to report it.” He added…