Problem of getting exact location using DFRobot_sim808.h by GSM808

Hello ! good day! it seems I can’t detect my location through google map. My code gives me latitude and longitude but when I open it, it gives me a wrong location. Can someone help me here ? I use this code because it’s easy for me to determine the speed of a vehicle using this but the problem is the accuracy of the location he gives. Currently using GSM808 and Arduino Mega

Here is my code:
#include <DFRobot_sim808.h>
#include <SoftwareSerial.h>
#define MESSAGE_LENGTH 160
char message[MESSAGE_LENGTH];
int messageIndex = 0;
char MESSAGE[300];
char lat[12];
char lon[12];
char wspeed[12];

char phone[16];
char datetime[24];

#define PIN_TX 10
#define PIN_RX 11
#define PHONE_NUMBER “+639096637389”
SoftwareSerial mySerial(PIN_TX,PIN_RX);
DFRobot_SIM808 sim808(&mySerial);//Connect RX,TX,PWR,

void setup()
{
mySerial.begin(9600);
Serial.begin(9600);

//******** Initialize sim808 module *************
while(!sim808.init())
{
Serial.print(“Sim808 init error\r\n”);
delay(1000);
}
delay(3000);

if( sim808.attachGPS())
Serial.println(“Open the GPS power success”);
else
Serial.println(“Open the GPS power failure”);
}

void loop()
{
//*********** Detecting unread SMS ************************
messageIndex = sim808.isSMSunread();

//*********** At least, there is one UNREAD SMS ***********
if (messageIndex > 0)
{
//*In order not to full SIM Memory, is better to delete it
sim808.deleteSMS(messageIndex);
Serial.print("From number: ");
Serial.println(phone);
Serial.print("Datetime: ");
Serial.println(datetime);
Serial.print("Recieved Message: ");
Serial.println(message);

while(!sim808.getGPS())
{

}

Serial.print(sim808.GPSdata.year);
Serial.print("/");
Serial.print(sim808.GPSdata.month);
Serial.print("/");
Serial.print(sim808.GPSdata.day);
Serial.print(" “);
Serial.print(sim808.GPSdata.hour);
Serial.print(”:");
Serial.print(sim808.GPSdata.minute);
Serial.print(":");
Serial.print(sim808.GPSdata.second);
Serial.print(":");
Serial.println(sim808.GPSdata.centisecond);
Serial.print(“latitude :”);
Serial.println(sim808.GPSdata.lat);
Serial.print(“longitude :”);
Serial.println(sim808.GPSdata.lon);
Serial.print(“speed_kph :”);
Serial.println(sim808.GPSdata.speed_kph);
Serial.print(“heading :”);
Serial.println(sim808.GPSdata.heading);
Serial.println();

float la = sim808.GPSdata.lat;
float lo = sim808.GPSdata.lon;
float ws = sim808.GPSdata.speed_kph;

dtostrf(la, 6, 2, lat); //put float value of la into char array of lat. 6 = number of digits before decimal sign. 2 = number of digits after the decimal sign.
dtostrf(lo, 6, 2, lon); //put float value of lo into char array of lon
dtostrf(ws, 6, 2, wspeed); //put float value of ws into char array of wspeed

sprintf(MESSAGE, “Latitude : %s\nLongitude : %s\nSpeed in kph : %s kph\nEMERGENCY !! Track my location here: \nhttp://maps.google.com/maps?q=%s,%s\n”, lat, lon, wspeed, lat, lon);

Serial.println(“Sim808 init success”);
Serial.println(“Start to send message …”);
Serial.println(MESSAGE);
Serial.println(phone);
sim808.sendSMS(phone,MESSAGE);
//************* Turn off the GPS power ************
sim808.detachGPS();

}
}